Understanding determinants related to farmers’ protective measures towards pesticide exposure: A systematic review

Objective Pesticide poisoning is the main cause of adverse effects and mortality worldwide. Protective measures can reduce the intensity of the effects of pesticides on the health of farmers. Numerous cross-sectional studies have been conducted on the determinants of performing protective measures to reduce exposure to pesticides, but there is no systematic study that comprehensively examines the impact of these factors. Therefore, the aim of this study is to identify existing studies on the determinants of effective protective measures to reduce exposure to pesticides among farmers. Methods In this systematic review, studies were obtained from PubMed, Web of Science and Scopus databases using a search strategy that covered articles from the first years of database design to April 20, 2023. The inclusion and exclusion criteria were based on the PICOs criteria. The study included cross-sectional studies that measured the implementation of protective measures using objective or valid subjective tools. The data were extracted and analyzed based on several criteria and ecological levels. The Ecological Model of Health Behavior was used to classify the determinants that affect the performance of protective behaviors. The National Heart, Lung and Blood Institute (NHLBI) has developed a quality assessment tool for studies. Results A total of 39 studies were ultimately selected for inclusion in this analysis. Many of these studies were conducted in developing countries. The most important factors that have an impact on protective measures include a variety of socio-demographic characteristics (age, gender, level of education, income, farming experience, experience of using pesticides), individual level (knowledge, attitude, risk perception, intention), interpersonal level (subjective norms), organizational level (education), and public policy level (government attention, health costs, governmental extension services). The quality of most studies was fair. Conclusions Research indicates that several factors influence the use of personal protective equipment and safe behaviors when handling pesticides. These include farmers’ education level, knowledge, and attitudes towards safety measures. Environmental factors such as access to information, extension services, training programs, and media coverage can also help minimize exposure to pesticides.


Introduction
Pesticides play a crucial role in controlling harmful or destructive pest species in crops, including insects, weeds, and disease-causing agents [1].Therefore, the use of pesticides is currently a key strategy in pest management to ensure food supply and distribution worldwide [2].However, reports indicate that some pesticides pose serious threats to human health and the environment [3].Several studies have shown that improper use of pesticides can increase the incidence of poisoning, disability, and death associated with pesticide exposure [4,5].
Pesticide poisoning is the main cause of adverse health effects and mortality worldwide.It is estimated that the annual incidence of pesticide poisoning among agricultural pesticide users in developing countries is about 18.2 cases per 100,000 people [6].However, estimating the actual incidence of pesticide poisoning among farmers in developing countries is difficult [7].Therefore, the use of pesticides has increased health risks for farmers [8].
The actions such as avoiding the health hazards of pesticides, adopting protective behaviors (PBs), using personal protective equipment (PPE), and appropriate use of pesticides during handling, transportation, mixing, and spraying are recognized as protective measures that can reduce the intensity of the effects of pesticides on the health of farmers [8,9].Most farmers do not consider the use of safety measures that can reduce the risk of pesticide poisoning [10].Therefore, identifying the effective factors on protective measures when using pesticides among farmers is essential [11].
A review of previous studies in the field of safety shows that various factors can influence protective measures among farmers when faced with pesticide poisoning [12].Factors such as age, education level, farming experience [13], perceived risk, awareness [9,10], attitudinal and belief variables [11], perceived barriers, facilitators, health expectations, social norms, emotions, physiological arousal, and intention are among the factors that determine the implementation of protective measures by farmers during pesticide use [14].
Many farmers who suffer from pesticide poisoning often do not report it due to concerns about losing their job, high costs, and lack of access to health care [6].Additionally, health care professionals often cannot accurately diagnose pesticide poisoning.Therefore, there is less reporting of pesticide poisoning among farmers [15].Furthermore, the status of protective measures and their effective determinants in a comprehensive study to reduce poisoning and exposure to pesticides is unclear [16].Numerous cross-sectional studies have been conducted on the determinants of performing protective measures to reduce exposure to pesticides, but there is no systematic study that comprehensively examines the impact of these factors.sample size, determinants examined in the studies, model or theory used in the studies, and study results.Additionally, the determinants were evaluated as independent variables at five ecological levels, and their impact on the dependent variable, which includes performing PBs or using PPE, was examined in the study.Demographic and background characteristics were also examined in the data extraction process.
Ecological levels.In this study, the Ecological Model of Health Behavior (EMHB) was used to classify determinants that affect the performance of protective behaviors [17].The first level of the model is the individual level, which is related to the knowledge, attitudes, and skills that are directly related to the individual.The second level is the interpersonal level, which includes the exchanges and interactions within an individual's network.This includes primary relationships, such as family and close friends, as well as secondary groups that are larger and more extensive.The third level is the organizational level focused on social institutions that act as official authorities and provide public and accepted goals.The fourth level is the community level, which includes relationships that organizations create with each other.These relationships are often found in coalitions.Finally, the fifth level is the policy and public policy level that is adopted by local and national governments.Ideally, when integrating and using this model, all five levels are taken into account.
Risk of bias assessment.The quality assessment tool for cross-sectional studies available from National Heart, Lung and Blood Institute (NHLBI), USA was used for quality assessment [18].This tool consists of 14 criteria that cover various aspects of the study design, methods, and analysis, such as the research question, the study population, the exposure and outcome measures, the confounding variables, and the statistical methods.For each criterion, researchers can answer yes, no, or other (CD, NR, NA), depending on whether the study met the criterion, did not meet the criterion, or they cannot determine, not reported, or not applicable.Researchers can also provide a quality rating (good, fair, or poor) for each study based on their overall assessment of the criteria.Quality is rated on a scale of 0 to 2, where 0 represents poor quality, 1 represents fair quality, and 2 represents good quality.The rating is determined based on the number of questions answered correctly out of a total of 14 questions.A score of 0-4 out of 14 questions corresponds to a rating of 0 (poor), a score of 5-10 out of 14 questions corresponds to a rating of 1 (fair), and a score of 11-14 out of 14 questions corresponds to a rating of 2 (good).NA stands for "not applicable" and NR stands for "not reported".

Identification of studies
Through electronic search engines and strategies, a total of 895 studies were identified.During the initial evaluation of duplicate and title, 817 of these studies were excluded as they did not meet the inclusion criteria (see Fig 1).Twenty nine articles were excluded during the evaluation of abstracts, resulting in a total of 49 studies for full-text assessment.After further assessment, a final selection of 39 studies was made for inclusion in the analysis.
Interpersonal level: Reinforcing factors in one study were considered as a determinant of protective measures [22].Also, subjective norms were considered in two studies [12,45].Social norm was also investigated in another study [14].
Organizational level: In eight studies, education to farmers about pesticides and exposure to them through governmental and private organizations were considered as an organizational factor [19,20,27,34,44,45,48,54]. Enabling factors [22] and access to materials [54] were also each investigated in one study.
Community level: At this level, only studies had examined two social [28] and environmental factors [54] that could affect protective measures.
Public policy level: The determinants of government attention, media coverage, enforcement of laws, and guideline access, in a study were investigated [54].In another study, governmental extensions services were considered for the impact on protective measures in exposure to pesticides [48].Also, in one study, health costs [38] and in another study, the source of information dissemination [25] were examined.

Determinants related to farmers' protective measures
In the following, the variables that had a positive effect on protective measures and had increased the performance of these actions are mentioned and the determinants that had no relationship are not explained.1) Demographic examined in studies The age of farmers had a statistically significant association with protective behavior to reduce exposure to pesticides [19,20,23,40,46,53].In three studies, gender had a statistically significant association with protective measures [23,33,42].Also, in thirteen studies, the results showed that the level of education of farmers had a statistically significant association with protective measures [19,20,29,30,33,37,44,46,48,[52][53][54][55].The income of farmers also showed a statistically significant association with protective measures in two studies [28,50].In three studies, farming experience [29,34,46] and in three studies, experience of using pesticides [24,39,55] showed a statistically significant association with protective measures.In one study, ethnicity [22] and in another study, alcohol consumption [19] had a significant statistical relationship with protective measures.
Interpersonal level: The constructs of reinforcing factors had a statistically significant association with protective measures [22].Also, both studies that examined the effect of subjective norms on protective measures reported a statistically significant association between the two [12,45].
Organizational level: Out of eight studies that farmers had considered the factor of farmer education by organizations, seven studies confirmed the association between acquiring these educations and protective measures [19,20,27,38,44,48,54].In addition, the access to materials had a statistically significant association with protective measures [54].
Public policy level: The determinants of government attention, media coverage, enforcement of laws, and guideline access, in a study were investigated [54], governmental extensions services [48], health costs [38], and source of information dissemination [25] had a statistically significant association on protective measures in exposure to pesticides.

Quality assessment
The quality of most studies was fair, and only five studies had good quality in the assessment by researchers [12,14,23,48,54].

Discussion
In this study, after careful examination of articles by researchers, 39 studies were identified in the field of determining the effective determinants of protective measures to reduce exposure to pesticides.In this systematic review, most studies were conducted in developing countries.In developing countries, farmers are at high risk of exposure to pesticides due to having smallscale agricultural land and gardens, as well as a lack of protective equipment, climatic conditions, and excessive use of pesticides [56].Contrary to our study, the systematic study by Afshari and et al (2021), which was conducted on interventional studies in the field of reducing exposure to pesticides in farmers, showed that most studies were conducted in developed countries, including the United States [57].Wiedemann and colleagues in a systematic study showed that in developing countries, extension services cannot reach the entire agricultural community due to insufficient budget [58].In wealthy and developed countries, strict regulations have been imposed for the use of pesticides, and exposure to toxic chemicals is prohibited or limited for farmers.While in developing countries, regulations and supervision of the use of pesticides are challenging and not implemented, and farmers are exposed to a large extent to toxic and vulnerable substances [59,60].So that, 1% increase in crop production per hectare is associated with a 1.8% increase in pesticide use per hectare.However, as countries reach higher levels of economic development, the growth in pesticide use intensity decreases [61].
The current study found that many studies have looked at how farmers' demographic and background characteristics (such as age, gender, education level, work experience, income, and training in pesticide use,) affect their use of protective measures.Of these factors, education level had the greatest influence on farmers' use of PPE.Many studies have found that farmers' education level and literacy are key factors in their use of PPE and safe management when handling pesticides [30,62].Farmers with higher levels of education are more likely to use PPE when handling pesticides [63].On the other hand, farmers who are illiterate or have low levels of education are at greater risk when working with pesticides and poisons on their farms.This is because they may not be able to read or understand instructions for using pesticides due to low literacy levels, which can lead to increased exposure and poisoning [64].
Also, among the demographic variables, studies showed a positive relationship between age and the use of PPE and PBs.The results of our study were consistent with other study, indicating that there was a positive association between age and the use of PPE [65].But contrary to our study, other study showed a negative relationship between age and the use of PPE [64], indicating that older farmers use traditional methods for crop cultivation and do not prefer the use of PPE for health.
This research investigated various ecological levels and found that the majority of studies focused on the individual level (such as knowledge and attitudes), the organizational level (such as pesticide training programs), and the interpersonal level (such as influential others).The majority of the training involved working with pesticides and using pest control poisons.There were very few studies conducted at the community level, despite the fact that community-level training is essential for all farmers in developing countries.There were also very few studies conducted at the public policy level, which included government extension services, law enforcement, media coverage, and government attention to providing farmers with access to guidelines, pesticide information resources, and health costs.Policymakers can help farmers by offering appropriate training programs to improve their agricultural skills and knowledge of how to reduce their exposure to pesticides.One way to provide training to farmers is through Farmer Field Schools (FFSs), where farmers can gain access to specialized knowledge [66].
In this systematic review, most studies measured farmers' knowledge and attitudes towards pesticides and the implementation of personal protective measures.The results showed that farmers' knowledge and attitudes towards the use of pesticides and the implementation of protective measures were good, and these two constructs were very effective in improving farmers' protective behaviors.Also, pesticide training programs have been very effective in increasing farmers' knowledge.Farmers who had more knowledge about pesticides used more PPE and had better PBs.In the study by Yassin et al, farmers reported high levels of knowledge about the impact of pesticides on health and performed most of the necessary protective measures when using pesticides [67].
The results of the study by O ¨ztas showed that knowledge of the safe use of pesticides is very insufficient, and this lack of knowledge negatively affects their quality of life as well as their occupational health and safety.To increase their level of knowledge, appropriate training programs should be arranged [68].
In general, improving knowledge and attitudes is not enough to change the behavior of farmers towards healthy and safe work, as these two are at the individual level.To prevent farmers from experiencing long-term effects when exposed to pesticides, planning should also be done on other levels of the ecological model [69].It is also necessary in other studies to pay attention to other constructs and factors, as well as to provide training programs as an organizational factor to increase the awareness and attitudes of farmers in developing countries.One notable point in this study was that the experience of working with pesticides and the experience of working on a farm were examined in the information, and in all these studies, farmers who had experience working with pesticides and farming experience had high awareness and attitudes in performing protective measures when working with pesticides [55,70].
Our findings also showed that the majority of studies did not use models and theories to examine behaviors.Only four studies had used a theory or model.Given that changing the behavior of farmers is difficult and many protective recommendations are never adopted by farmers, to improve the behavior of farmers, multiple studies should be conducted with the aim of addressing all levels of the ecological model (individual, interpersonal, organizational, community, and public policy level) and using appropriate models and theories to overcome barriers such as providing necessary financial resources, offering formal training, and access to government extension services.
Most of the studies examined in this systematic review were of fair quality.Similar to our study, another study in this field found that most studies were of low quality [57].However, in the systematic review by Sapbamrer et al. on the factors affecting the use of PPE and safe pesticide practices, it was shown that most studies were of good quality.This can be explained by the fact that these studies were cross-sectional and received lower scores on some items due to their cross-sectional nature and were classified as low-quality studies [71].
This study had limitations due to the differences in the primary and secondary outcomes measured, as well as the small sample sizes used in the study designs.These factors made it difficult for us to determine an overall effect size or to perform a meta-analysis.

Conclusion
Research has shown that there are several key factors that influence the use of PPE and safe behaviors when handling pesticides.Among demographic factors, farmers' education level and age have been found to be important, while among behavioral and psychological-social factors, farmers' awareness and positive attitudes towards safety measures have been shown to promote the use of protective measures.Environmental factors, such as access to information about pesticides, extension services, formal training programs, and media coverage, can also help minimize exposure to pesticides and should be prioritized in public policy.Extension services provided by the government can play a crucial role in raising awareness about safe pesticide use through training programs that are tailored to farmers' education levels and regularly updated.Policymakers and governments should prioritize increasing farmers' knowledge about using fewer toxic pesticides, especially in developing and poor countries.Additionally, the long-term health effects of pesticide exposure and the benefits of protective measures should be taken into account.